From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-45974][MODERATE REGULAR] btrfs: fix invalid leaf access in btrfs_quota_enable() if ref key not found [ Upstream Date: Wed, 27 May 2026 09:02:02 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-45974 X-AL-KERNEL-Priority: MODERATE REGULAR X-AL-KERNEL-Severity: MODERATE REGULAR X-AL-KERNEL-Base-Severity: MODERATE X-AL-KERNEL-KPANIC: NO X-AL-KERNEL-ActionableScore: 3 X-AL-KERNEL-ActionableScore-Lower: 1 X-AL-KERNEL-Commit: 023545e272f369d487e6a986c1e321c6e04be1da List-Id: CVE: CVE-2026-45974 Priority: MODERATE REGULAR AL-KERNEL base severity: MODERATE KPANIC flag: NO Patch: btrfs: fix invalid leaf access in btrfs_quota_enable() if ref key not found [ Upstream Commit: 023545e272f369d487e6a986c1e321c6e04be1da Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=023545e272f369d487e6a986c1e321c6e04be1da Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-45974 Analysis date: Wed, 27 May 2026 09:02:02 -0400 ActionableScore: 3 ActionableScore lower bound: 1 Actionable bucket: Borderline, manual review recommended Manual review required: YES Summary: No one-sentence report phrase was found. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-45974 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-45974 The original announcement does not normally provide a security severity estimate, CVSS assessment, or enough information to determine whether the reported kernel bug represents a practically relevant security issue. This report was generated by AL-KERNEL, an AI-assisted Linux kernel vulnerability analysis system developed by Alexander Larkin. It combines an autonomous classifier with LLM-assisted technical analysis and a separate ActionableScore mechanism. The purpose of this report is to prioritize Linux kernel CVEs before manual review, identify cases that require prompt investigation, and support automatic closure of issues that are unlikely to have meaningful security impact. Published priority for this report: MODERATE REGULAR Manual review required: YES A detailed explanation of the methodology and priority rules is included at the end of this message. ====================================================================== AL-KERNEL CLASSIFICATION RESULT ====================================================================== CVE-2026-45974 MODERATE CHECK Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:H/PR:H/UI:N/S:U/C:L/I:L/A:H';CWE-754;CWE-703;CWE-125;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '5.2';DESCR 'btrfs_quota_enable could continue scanning after btrfs_search_slot_for_read indicated that the search reached the end of the tree and the current path was no longer valid. A later btrfs_next_item call could then operate on an invalid path or leaf while enabling qgroups, which may lead to a kernel crash or incorrect filesystem metadata handling. For the CVSS the PR:H is used because enabling Btrfs quotas normally requires administrative filesystem control such as CAP_SYS_ADMIN. The issue is not network reachable and is triggered through a local filesystem management operation. Impact is mainly availability, with low confidentiality and integrity concern only in the paranoid interpretation because the bug is an invalid metadata tree access rather than a proven memory corruption primitive.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline, manual review recommended (with actual score 2) YES DISK SIMPLEFIX SKIP INCREASED_FROM_LOW_BASED_ON_REQUIREMANUALCHECK DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5 YES NO checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=3 ActionableScoreLower=1 1. ActionableScore * Conservative score: 1 * Paranoid score: 3 * Final recommended bucket: **Borderline, manual review recommended**:: 2. Signal breakdown * Reliable kernel crash / strong DoS: +1. Continuing with an invalid Btrfs path can lead to invalid leaf access and likely crash or abort in filesystem code. * Important filesystem/storage path: +1. The bug is in Btrfs qgroup quota enable logic and touches filesystem tree metadata traversal. * Availability impact realistic: +1. Invalid metadata path access during quota enable can disrupt filesystem management and may crash the kernel or fail the operation. * Integrity impact plausible in paranoid scoring: +1. The affected code walks filesystem metadata, so incorrect traversal has a limited theoretical metadata integrity concern, although no write corruption primitive is shown. * Requires admin/root/CAP_SYS_ADMIN in typical deployments: -2. Enabling Btrfs quotas is an administrative filesystem operation. * Weak corruption only: +0. The patch shows invalid path or leaf access, but not UAF reclaim, OOB write, arbitrary write, page-cache corruption, or controlled overwrite. * No remote reachability: +0. This is not packet-triggered or network exposed. 3. Reachability analysis The bug is triggered through local Btrfs quota enable operations. In normal deployments this requires CAP_SYS_ADMIN or equivalent administrative filesystem control. User namespaces or containers usually do not make this directly reachable against the host filesystem unless a privileged container or management service is allowed to operate on the host Btrfs mount. The path is not default-triggered by ordinary file I/O and is not remotely reachable. Realistic exploitation is mainly an admin-triggered crash or filesystem management failure. 4. Severity interpretation This behaves like a low to borderline Moderate filesystem bug rather than an Important-class vulnerability. The theoretical concern is invalid metadata tree access in an important filesystem subsystem. The realistic evidence supports DoS or operation failure, not privilege escalation or controlled memory corruption. Because filesystem metadata paths can have non-obvious side effects, manual review is reasonable, but the CAP_SYS_ADMIN requirement keeps practical urgency low. 5. One-sentence report phrase Btrfs quota enable could continue after reaching the end of a metadata tree search and operate on an invalid path or leaf, causing a local administrative DoS risk during qgroup setup. 6. Manual review recommendation MANUAL CHECK RECOMMENDED The bug affects an important filesystem metadata traversal path, but it requires administrative Btrfs quota management and does not show a strong memory corruption or LPE primitive. ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: btrfs: fix invalid leaf access in btrfs_quota_enable() if ref key not found [ Upstream Commit: 023545e272f369d487e6a986c1e321c6e04be1da Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=023545e272f369d487e6a986c1e321c6e04be1da Changed files: fs/btrfs/qgroup.c Diff excerpt: Not included in this email. See the upstream URL for the full patch. Full patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=023545e272f369d487e6a986c1e321c6e04be1da ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-45974 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-45974 The original CVE announcement normally does not include a security-level estimate. In particular, it may not contain a CVSS assessment, an impact level, or enough information to determine whether the reported bug is a practically relevant security issue. One purpose of this parallel CVE list is to provide that missing technical and prioritization information. The original goal of the AL-KERNEL project was to prioritize Linux kernel CVE analysis automatically before manual review. The system can also help identify non-security issues that may be suitable for automatic closure. This report was generated by AL-KERNEL, an AI-assisted Linux kernel vulnerability analysis system developed by Alexander Larkin. The first analysis stage combines an autonomous classifier with additional LLM-based analysis. The autonomous classifier runs locally on a CPU and is based on a backpropagation neural network. Together, these mechanisms produce a technical vulnerability description, identify likely weakness types, estimate CVSS severity, and provide input for ActionableScore. Two CVSS estimates are retained because incomplete kernel vulnerability information often permits more than one defensible interpretation: Conservative CVSS vector: AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H The Best / paranoid CVSS vector: AV:L/AC:H/PR:H/UI:N/S:U/C:L/I:L/A:H The Best / paranoid CVSS score: 5.2 The conservative vector represents a lower-impact interpretation. The Best/paranoid vector intentionally represents a plausible upper-bound interpretation and should not automatically be treated as demonstrated real-world impact. CVSS may also need to be adjusted for a particular Linux deployment, because actual reachability, privileges, enabled kernel configuration, hardware, namespaces, exposed device nodes, and other environmental conditions can differ significantly between systems. A separate ActionableScore mechanism evaluates practical remediation urgency. Its analysis may include reachability, attack prerequisites, subsystem exposure, memory-corruption characteristics, denial-of-service reliability, and possible confidentiality, integrity, or privilege-escalation impact. Conservative ActionableScore: 1 Paranoid ActionableScore: 3 The final base severity is taken directly from the second tab-separated field of the AL-KERNEL classification result. ActionableScore does not replace or independently override that final AL-KERNEL decision, and if ActionableScore adjusted impact level of ALKERNEL, then you would see self-readable flags above like INCREASED_TO_HIGH_BASED_ON_ACTIONABLESCOREHIGHEREQTHAN7. For an AL-KERNEL result of MODERATE, this report uses the following additional presentation split: ActionableScore below 5 -> MODERATE REGULAR ActionableScore 5 or more -> MODERATE 7.0 The distinction between MODERATE REGULAR and MODERATE 7.0 makes it possible to identify Moderate issues that should receive manual analysis and fixes before lower-priority MODERATE REGULAR issues. In many cases, MODERATE REGULAR fixes may wait for a later rebase or routine update. There is one override in which MODERATE REGULAR becomes MODERATE 7.0 even when the ActionableScore is below 5. When the AL-KERNEL result contains the KPANIC flag, a MODERATE result is always presented as MODERATE 7.0. The KPANIC flag selected with few regexps without usage of AI at all, so it helps to detect cases when Kernel Crash happens and similar (to filter False-Negative results from the LLM usage). KPANIC indicates that a reliable kernel crash, kernel panic, or similarly serious kernel availability impact was identified by the classification workflow. AL-KERNEL base severity for this report: MODERATE KPANIC detected for this report: NO Published priority for this report (same as in Subject): MODERATE REGULAR These results are intended to support engineering triage. They are machine-generated estimates, and cases marked for manual review should be validated by a human security engineer before final disposition. For more info read docs linked from here: https://kernelcve.org/ (and you can submit you own patch there to generate such a report for non-existant CVE-id yet). Note that in many cases this AI tool selects higher severity, than real is (means you can expect Importants instead of Moderate 7.0 or Moderates 7.0 instead of regular Moderates). If you see such cases, please use reply email interface to add additional manual analyses info to this particular CVE. And please, please, let me know when you see Lows instead of Importants or Important instead of Low (because particular for such cases I need to tune this AI tool to make it better for this one and next similar). My contact email for such notifications is alexanjelausa@gmail.com (and both send reply to CVE record itself too and see "reply" button below for howto reply).